I frequently send between 200 and 400 emails, either personally or as part of an association, and I would like to know what the real impact of these emails is.I discovered yesterday the existence of Mail CHIMP and MailJet which are used to make mass mailings and have tracking and statistics features.But I would prefer, if it exists, to use an open source software or, better still, an application that I would install on my computer.Could you advise me on this matter?